How to Pimp My BMW 325xi

1. Modify the 325's interior by installing an aftermarket shift knob. These are available in a variety of finishes and looks, from wood or leather to brushed or polished aluminum. You can also install a short shift kit to make shifting more efficient and sporty feeling. Next, swap out the stock steering wheel for something smaller and sportier. One of the biggest changes you can make is the installation of aftermarket seats like the ones from Recaro. These look better than the stock seats, though they may not be quite as comfortable depending on the model you choose.
2. Modify the 325's exterior. BMW offers their own line of OEM exterior parts for the E90 (the latest 3 Series) generation of cars that look more aggressive than stock but are better quality than most available aftermarket parts. You can also turn to the aftermarket. Once you've got a body kit painted and installed, have the windows tinted darker for a more dramatic appearance. You can also install a variety of carbon fiber accessories like headlight eyebrows that give the car a more menacing appearance.
3. Install a lower suspension to not only increase the performance of your BMW, but also make it stand out from a sea of stock ride-height vehicles. You can either install spring and shocks or go for a full coilover suspension, though the latter is more expensive. Also bolt in a big brake kit from a company like Brembo. Not only will the car stop better with bigger brakes, but the brake calipers look better than stock.
4. Install a larger set of aftermarket wheels and wider tires. There is a huge selection of wheels available online and at tires stores like Discount Tires. Performance tires go a long ways towards making your car handle much better.
5. Increase the performance of your BMW. Install a retuned ECU, which will have more aggressive mapping for the fuel and ignition curves and free up more power. On the exhaust end, install a free-flowing exhaust to let everyone know your coming. You can also install a cold-air intake, adding power and noise.